Slide 1
Galaxies trace a cosmic web of filaments and voids
On very large scales, galaxies cluster along filaments and around broad, sparsely populated voids. This network is called the cosmic web.
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The word web is a description of distribution, not a literal material net. It organizes galaxies and matter across scales much larger than an individual galaxy.
Slide 2
Groups and clusters occupy denser connected regions
Galaxy groups and clusters occupy denser parts of the pattern. Filamentary structures connect some of these concentrations across large distances.
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A sky photograph projects depth into two dimensions. Surveys need distance information to distinguish a true filament from unrelated galaxies that happen to line up along our view.
Slide 3
A void is sparse rather than completely empty
Cosmic voids contain much less matter than surrounding regions. They are not necessarily completely empty of galaxies or diffuse material.
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The contrast depends on the scale and population being measured. Describing a region as a void is a comparison with the wider density pattern, not proof that no particle or faint galaxy exists there.
Slide 4
Gravity grows structure from early density differences
In cosmological models, gravity grows structure from early density variations. Dark matter and ordinary matter both contribute to the resulting pattern.
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Simulations can show the predicted distribution of matter, including components that do not emit visible light. Such images visualize a model and must be tested against observations rather than treated as direct photographs.
Slide 5
Surveys test how the pattern develops
Large surveys measure how structure changes across distance and time. Those measurements help constrain models of gravity, matter and expansion.
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Different surveys detect different tracers, such as galaxies or gravitational lensing. Combining them helps check whether the inferred structure depends on one instrument’s selection effects.
Sources
- The Distribution of Galaxies in Space
OpenStax, Rice University
- The dark cosmic web
ESA
- Top five mysteries Euclid will help solve
ESA